I have up for sale a Mean Well S-350-27 SMPS Power Supply. The Voltage is adjustable from 24-32v. Well Built 13amp unit. Works well as amp or preamp power supply (single rail--positive voltage only). Used for less than 1 hour. Dual voltage so it will work in any country (100-240vac, 50/60hz).

These are selling on Ebay through Hifimediy for $49. Buy mine for $35. I even have the original box.